Drilling machine drive



July 13, 1954 J. GERENTES 2,683,375

DRILLINGMACHINE DRIVE Filed May 26, 1950 s Sheets-Sheet 1 mvvnFor 72m GRE/VTES 5 mm AH-orncy July 13, 1954 J GERENTYES DRILLING MACHINE DRIVE Filed May 26, 1950 -3 Sheets-Sheet 2 I IEIII, 1 LIZ I Ill I 7751/11/12 '9 M Q 1 Q o J AIS. A h A .1 O 9 0 3 m H 5 1 4 1 1 JEAN 6' July 13, 1954 J. GERENTES DRILLING MACHINE DRIVE 3 Sheets-Sheet 3 Filed May 26, 1950 3' van H v RE/v-rs AH-or-n ey Patented July 13, 1954 DRILLING MACHINE DRIVE Jean Gercntes, Saint-Etienne, France, assignor to Constructions Electro-Mecaniques de Saint- Etienne Ancienne Usine Wageor, Saint- Etienne (Soire), France, a French body corporate Application May 26, 1950, Serial No. 164,570

Claims priority, application France May 27, 1949 3 Claims. 1

In his U. S. A. patent application No. 21, 649 filed on April 17, 1948, now Patent No. 2,547,079 issued April 3, 1951 the applicant has described a drilling machine with variable feed in which the drill, or similar tool, is rotated by a principal electric motor with normal rotor slipping, while the longitudinal backwards and forwards motion is provided by the differential actions of this principal motor and of a reversible auxiliary motor with a high rotor slip, said auxiliary motor being controlled by a reverse and stop switch.

In the embodiment described in the abovementioned patent application the machine is fixed and the drill is secured on the end of a screw having a helicoidal motion composed of the rotary motion due to the principal motor and of a longitudinal motion varying automatically with the hardness of the material to be drilled and due to the differential actions of the two motors.

The present invention has for its object an improved drilling machine which makes it possible to drill a hole of great length in a single operation while the length of said machine is shorter for a given depth of hole than that of thev machine according to the aforesaid embodiment.

The invention has more particularly for its object a machine which comprises in combination: an elongated stationary frame; a carriage moving along this frame; a boring tool journalling.; i

in this carriage from which it projects and whose axis of rotation is parallel to the direction of the motion of said carriage; a lead screwed shaft which rotates in said frame and whose axis is also parallel to the direction of motion of saidw.

carriage; a nut screwed onto said screwed shaft and journalled in said carriage; a principal electric motor mounted on this carriage and providing the rotary motion for this tool and screwed shaft; an auxiliary reversible electric motor with function of the relative speeds of rotation of said lead screw shaft and said nut.

In the accompanying drawings which are given solely by way of examples:

Fig. 1 shows an outside view of the machine mounted on its base;

Fig. -2 shows an elevation view of the machine mounted on its frame with a partial longitudinal section and diagrammatic representation of the various driving mechanisms;

Fig. 3 shows a top view of the same machine with its frame;

Fig. 4 shows a detailed cross-sectional View of the variable feed mechanism;

Fig. 5 is a vertical cross section along the line 55 of Fig. 1 but to a larger scale showing the drill guide;

Fig. 6 is a rear View of the drilling machine mounted on its frame, this view corresponding to a cross-section along line -6-6 of Fig. 1;

Fig. '7 is a diagram of the electric circuit;

Fig. 8 is a perspective view, partly in section, of the principal motor switch and of a hand switch;

Fig. 9 is a diagram of the auxiliary motor reversing switch and of an auxiliary switch connected with end of run switches.

According to the embodiment shown, a carriage i0! slides by means of four bearings :92 on two rods I03 rigidly assembled with two braces Hi4 and I05.

The assembly I63, I04, I05 forms a frame which is provided at its ends with extensions 106 and H31 by means of which it can be mounted on some support device (not shown on drawing) appropriate for the work to be done and which serves to direct the entire assembly, by conventicnal means, in the direction for boring several holes. In addition a shock-absorbing spring 08 surrounds each rod I33 near the front brace I05.

On carriage H0! is secured a principal motor Ml the rotor of which is shown at I99 (Fig. 2). This motor drives, by means of a gear consisting of toothed wheels H0, Ill, H2 and H3, a shaft H4 into which fits the drill H5.

- This same motor M1 also drives, through a gear consisting of wheels Hi and H 3, a screwed shaft Ill. This shaft is mounted in the frame in such a way that it can rotate at both ends in the braces I04 and I05 but without possibility of moving longitudinally. It is provided with longitudinal grooves H8 (Fig. 4) into which fit keys I l 9 carried by the wheel H5.

On carriage llll is also mounted an auxiliary motor M2 with a high rotor slip (i. c. with large variation (W of the speed for a given variation 03C of the torque, the term dV representing speed variations and the term dC representing variations of the torque; the ratio of the variation ciV with respect to the variation (20 representing mathematically the derivative of the relation between the speed V and the torque C; thus, the term (W is the variation of V for an infinitely small variation d of the torque C) This motor M2 which is reversible can, for instance, be an asynchronous squirrel cage motor with particularly high resistance.

Only the rotor I26 (Figs. 2 and 4) of this motor M2 is shown. This rotor I26 drives, by means of a gear consisting of elements IZI and I22, a removable nut I23 keyed on the hub of the wheel I22, for instance on the tip of this hub by one or several radial projections I23 provided on this nut and which fit into grooves in the side of said hub. The nut I23 is locked longitudinally by a nut I25 (Fig. 4) screwed on said hub and in contact with said projections 523 Said hub of the wheel I22 is journalled by means of two bearings I25 and H26 in the frame of the carria e IIlI.

In order to facilitate the starting of the drilllng operation the machine is provided with a guide located in front, on brace I05. This guide, in which the drill [I is centered, can easily be disengaged once the hole is begun. It consists (Fig. 5) for instance, of two half rings I2! and I28 in which are inserted and secured half bushings I29 and I3!) which act as friction elements. These half rings swing respectively about pins I3I and I32. They are pressed on one hand one against the other and on the other hand against a stationary stop I34 which keeps the shaft in a fixed position, by a bolt I35 hinged at 35 to one of the half ringsJ This bolt fits into a notch I31 in the other half ring and is provided with a nut I38.

When the machine is set in motion these half rings are opened down towards the brace I95, then after the drill has been inserted in the machine they are clamped together as shown in Fig. 5.

The power supply and its control for the two motors M1 and M2 can, for example, be provided in a manner similar to that described in the aforesaid U. S. A. application No. 21,649, new Patent No. 2,547,079 issued April 3, 1951 or again in the manner shown in Fig. '7.

According to this embodiment, a five-pin plug I39 connects five conductors (three main conductors I46 and two pilots I4I) of a cable I42 to conductors it and I4! respectively of the machine.

The other end of the five wire cable is connected in a box I43 to some standard contactor switch Its the operating coils I45 of which can be put in or out of circuit by control switches mounted on the machine and connected to leads Mi as hereafter described.

The windings I 46 of the main motor M1 are connected to wires Mil through a double pole switch It! actuated by a lever It! (Fig. l). The windings I48 of the auxiliary motor M2 are connected to the same wires Mil through a doublepole reverse switch I49 which is actuated by a lever I49 (Fig. 1).

The coil I45 of contactor I44 is controlled through the combination of three switches I5, I5I and I52 in series between the two wires MI and through auxiliary reverse switch I53 which may short-circuit one or the other of the switches I5I and I52 according as its moving element is iigzcontact with the contact I5I or the contact I Switch I50 is a mechanical starting switch. It is operated by a push-button I50 (Figs. 1, '7, 8) coupled with the switch 14'! 59 th t t the lever IQ'I is at rest or is slightly ahead of the closed position of the switch in the direction of closing of this switch.

The lever It? actuates the moving part of the switch I51 by means of a rod I52. A spiral or other spring I55 tends to rotate the shaft I5 8, the lever IG'I' and the moving part of the switch I57 in the direction of the arrow f corresponding to the return of the switch to the ofi position with the switch open and the main motor M1 not in operation. On the shaft IEQ is keyed a disc I56 the cylindrical surface of which has a groove I5? with flanges I58 and 59 on either side. 'The flange I58 is provided with two notches I56) and IBI. Between these notches E68, iSI, starting at notch I60, the flange I59 carries, along a short length on its outer surface, a recess I52 which ends at a shoulder I63.

fhe push-button 155 of the starting switch IE8 is brought to the off position (switch open) by a spring 564. This button carries a pin I65 guided by a fixed fork IE5.

The relative position of switches it": and It? is such that when they are both at rest the end of pin I65 is in the groove I5? of the disc I55 and faces the notch Iiaii. Furthermore the angular distance between the two notches I60 and NI is slightly greater than the angle through which lever Ml must be rotated to bring the switch from the open to the closed position (position Ill? of lever Ml).

Besides, the axial travel of push-button I559 is sufiiciently small so that at the end of its down ward movement the end of pin 5 65 is:

(a) On the one hand, at such a level that it is still partially in the notch Iti! if it faces this notch;

(12) On the other hand, at such a level that it can enter the recess I52 when it is in notch Under these conditions it is clear that:

At rest, the push-button 158- can be operated but the switch 14? is then locked by the pin 65 which is and remains (because of condition a above) in the notch I even if the button I5ii is pushed;

If the lever It? is first turned as far as MI thus closing the switch I l'i, the pin IE5 remains in the groove I5! and the switch iii-i; cannot be closed;

To close this switch, the lever I l? must be further rotated beyond the normal closed position Iti in the direction opposite to arrow 1 I, so that as to bring the notch it! opposite the pin I 55 the button iiifi can then be pressed, providing the lever ssi is temporarily kept in its extreme position, then as soon as pin I55 has passed the narrowest part of the flange I59 (on the side of the recess I52) the lever It? can be released and the spring I55 will bring it back to I il' This ensures mutual interlocking:

On the one hand, of the switch E50 in the closed position, the pin I55 bearing against the flange I59 in the recess I62; and

On the other hand, of the switch IQ! in the closed position because the spring I55 is prevented from bringing the switch back to the open position since the shoulder I63 rests (from the above-mentioned condition b) against the pin I85 which is itself held by the guiding fork I66.

In order to bring the two switches back to rest, the lever Mi must be brought a little ahead of the position t tl in the direction opposite to the arrow f so that the notch ISI faces the pin N35. The spring H54 returns this pin into line with the groove i5! while the switch I50 opens. Finally the lever of switch I 47 should be released, and it is then brought to rest, as well as the switch, by the spring I55.

The switch I5I is an end of forward run" switch. It is located on the moving part of the machine and is actuated at the end of the forward run of the carriage IGI by a stop i6"! (Fig. 3) located on the front brace I05.

Similarly, the switch I52 is an end of baclrward run switch; it is located on the moving part of the machine and is operated at the end of the backward run. of the carriage IOI by a stop its located on the rear cross-piece I I34 (Figs. 1 and 3).

As to the auxiliary reversing switch I5 3, it is interlocked with the double-pole reversing switch I59 of the auxiliary motor M2 so that both are automatically and simultaneously operated and that at the end of a run in a given direction the switch i5. short-circuits the switch I 5| or I52 which has just been opened, and this as soon as the reverse switch I39 is put in the position corresponding to the run in the opposite direction.

The effective form of the interlocking reversing switches M9 and I53 is not diflicult to achieve, it can be done in a well known way by using a contact drum-controller.

9 shows diagrammatically such a device. The operating lever I 19 is integral with a shaft it? onto which are keyed two discs or drums 55 and 553. On drum I68 are the usual (not represented on diagram) contacts of the reverseswitch 49. on the disc I53 are two contacts its and I'Iil which rub respectively against the fixed contacts I5! and I52 while the disc I53 is in permanent contact with a fixed contact I 5! contact I5! is connected (Fig. '7) with the contacts which are in series of the switches Hi and 552 while contact I5I or I52 is connected with the other contact of switch I5I or switch 552 respectively.

The machine operates as follows:

Said machine being at rest, the carriage IIH is supposed to be at some intermediate point of its travel so that the end of run switches I5I and E52 are closed. On the contrary, the following switches are open: the main motor M1 switch 54?; the reversing-switch I49 of the auxiliary motor M2; the starting-switch I 59 the switch I53.

First, the switch M! is closed by turning the lever Mi in direction opposite to that of the arrow f (Fig. 8) until the notch I6I faces pin I55. Then the button I50 of switch I5!) is pressed in order to close said switch. The tip of the pin I55 comes below the higher side of the recess 52 of the disc I56. The lever Mi is then released, the spring I 55 brings it back to the position I 51" the pin I65 is then in the recess I 6i? and bears against the shoulder I63 thus keeping the two switches I41 and I50 in the closed position.

The circuit of the coil I45 of the contactor I44 is then closed since the three switches I 50, I5I

and I52 (which are in series) are closed. The contactor I44 closes and the main motor M1 starts as its windings I46 are energized.

Now the lever I49 is rotated in the direction which closes the double-pole switch :49 of the auxiliary motor M2 so that said motor M2 rotates in the same direction as the principal motor M1; under these conditions, the rear switch IE2 is short-circuited by the switch I53 which is automatically brought into the position shown in Fig. 7 by the operation of the lever M9 because of the looking arrangement shown in Fig. 9.

The rotor 289 of the main motor M1, drives the tool holder wheel H3 and thus the drill I I5, it also provides the rotary motion, but the rotary motion only, of the screw I H.

The rotor I 28 of the auxiliary motor M2 provides the rotary motion, but the rotary motion only, of the nut I23.

The relative speeds of this not H3 and of the screw Ii? causes a forward longitudinal displacement of the nut and so of the carriage IDI and the drill-bit H5. Indeed: let V; be the speed of rotation of the screw H? which is due to the main motor M1, and V2 be the speed of the nut which is imparted to it by the auxiliary motor M2; the speed of the feed motion is (V2V1) X72, 7) being the pitch of the screw. The speed of revolution of the drill H5 is M71, is being a factor which depends on the ratio of the gear train connecting the drill and the screw to the rotor I09.

As regards the distribution of the energy supplied by the main motor M1 and the auxiliary motor M2, it can he assumed, with a sufficient degree of approximation, that the principal motor M1, provides the drilling energy (torque C1) and that the auxiliary motor M2 provides the energy for the feed (torque C2).

The slipping of the rotor of the feed motor being much greater than that or" the rotor of the principal motor, it results:

We QB (1C d0, and

In the foregoing formulas the terms 0W2, dVi, (1C2, and 101, have the same mathematical mean ing as explained heretofore in connection with the terms CW and dC, except that here the term (ii '2 represents the variation of speed which corresponds to the Variation 1102 of the torque sup plied by the auxiliary motor M2, and that (5V and dC1 are corresponding terms applicable to the principal motor M1. The first of the two formulas just reproduced merely means that for an equal variation of the torques. in which (1C1 equals (1C2, the variation of speed is greater for the motor M2 than it is for the motor M1. Since the opposing torques are approximately proportional to the hardness of the material, it may be written:

do in 01R 01R as the absorbed power will be limited by the main motor M1. This condition will be reached for theoretically infinite material hardness.

For the hardness of each material to be drilled there is a point of stable operation at speeds V1 and V2 corresponding to the powers P1 and P2 of each of the motors depending on the conditions of their construction and particularly on the ratio of each motor. When the drill has finished its work of drilling, the carriage iii! is near the cross-piece Hi5 and presses against the shock-absorbing springs I98.

The switch 154 is then opened by the pushbutton. 15?. reversing-switch $53 then shortcircuits the end of backward run switch the switch 15 which is not short-circuited, opens the circuit of the control coil M5,; the contactor M3 opens and the machine, being no longer supplied with power, stops.

The lmob i i-2 must then be rotated in the opposite direction, this operates the reverse-switch his of the auxiliary motor M2 and reverses the position of the switch 153 which short-circuits the open end of the forward run switch iEl.

Power is again supplied, the auxiliary motor M2 revolves in the opposite direction and the carriage it! rapidly runs backward while the switch 55! is simultaneously closed by its spring.

At the end of its backward run, the machine reaches the brace Hit and stop E63 opens the end of backward run switch 52 thus stopping the machine again.

To recommence the operation, the reverseswitch 550 must first be set to the forward running position, this short-circuits the switch I52 with the reverse switch I53 and so on.

The machine according to the invention offers important advantages compared to those described in the above-mentioned patent application: by using a very long drilling tool a very long hole can be drilled in one operation without risk of buckling of this tool because of the front guide; this saves a considerable amount of time; the rigidity of the machine is increased.

Furthermore, the machine takes up less space because the distance from the rear of this machine to the working face is approximately equal to the length of the hole to be drilled whereas in the form described in the aforementioned patent application the machine, in its starting position, is at a distance from the working face already equal to the depth to be drilled and it is necessary to have behind this machine the length of screw required for the distance which the drill-bit has to travel.

Naturally, the invention is in no wise restricted to the embodiment shown and described which was only chosen as an example.

Obviously the various controls can be carried out either by the operation of the switches and reversing switches described and which are in the total supply circuits, or else with ordinary and reverse switches in small current circuits operating contactors or relays.

Having now described my invention what I claim as new and desire to secure by Letters Patent is:

1. A gear drive comprising a stationary frame, a screwed shaft carried by said frame, a carriage (ill movable along said frame, a rotary tool journailed in said carriage, said tool and said shaft having parallel axes, a nut screwed on said shaft and carried by said carriage, said screwed shaft and said nut being respectively rotatahly rncunt ed in said frame and in said carriage, a main electric motor and an auxiliary reversible electric motor, both said motors being carried by said carriage, supply circuits for said motors, a first mechanical driving means between the rotor of said main motor and said tool and shaft and adapted to drive said tool and shaft simultaneously, a second mechanical driving means between said nut and the rotor of said auxiliary motor and adapted to drive said nut at a speed higher than the speed of rotation of said screwed shaft, said auxiliary motor having a high rotor slip, and a reversing switch inserted in the supply circuit of said auxiliary motor.

2. A gear drive comprising a stationary frame, a screwed shaft carried by said frame, a carriage movable along said frame, a rotary tool journalled in said carriage, said tool and said shaft having parallel axes, a nut screwed on said shaft and carried by said carriage, said screwed shaft and said nut being respectively rotatably mounted in said frame and in said carriage, a main electric motor and an auxiliary reversible electric motor, both said motors being carried by said carriage, supply circuits for motors; a first set of two partially common trains of gears between on the one hand the rotor of said main motor and on the other hand said tool and said shaft and adapted to drive there simultaneously, a second train of gears between the rotor of said auxiliary motor and said nut and adapted to drive said nut at a speed higher than that of said shaft, said auxiliary motor having a high rotor slip, and a reversing switch inserted in the supply circuit of said auxiliary motor.

3. An electric gear drive comprising an elongated stationary frame provided with at least one rectilinear slideway, a screwed snaft journalled in said frame, a carriage movable along said frame, a rotative tool journalled in said carriage, the axes of said shaft and tool being parallel to said slideway, a nut screwed on said shaft and iournalled in said carriage, a main electric motor carried by said carriage, a first mechanical driving means between on the one hand the rotor of said main motor and on the other hand said tool and shaft adapted to drive them simultaneously, an auxiliary reversible electric motor carried by said carriage and hav ing a high rotor slip, other driving means between the rotor of said auxiliary motor and said nut to drive said nut at a speed higher than that of said screwed shaft, supply circuits for said motors, and a reversing switch inserted in the supply circuit of said auxiliary motor.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,023,841 Kingsbury Dec. 10, 1935 2,240,795 Morgan May 6, 1941 2,244,127 Smith June 8, 1941 2,365,681 Gartin Dec. 26, 1944 2,432,313 Heumann Dec. 9, 1947 2,434,120 Paget Jan. 6, 1948 2,520,014 Rehnberg Aug. 22, 1950 2,547,079 Gerentes Apr. 3, 1951 

